Safety headrest for a motor vehicle

ABSTRACT

A vehicle seat ( 1 ) as a head-rest ( 5 ) which is mounted for movement about a horizontal axis defined by a bar ( 7 ) depending arms ( 12 ) extend downwardly into the back of the seat and carry a pressure plate ( 13 ) at a position behind the torso of the occupant of the seat so that pressure applied to the pressure plate ( 13 ) will cause the head-rest ( 5 ) to move forwardly. The pressure plate ( 13 ) is pivotally connected ( 14, 15, 16, 17 ) to the arms ( 12 ) to enable the arrangement to pivot to the maximum extent in a situation where the rear part of the seat is rigid, for example if the seat is a rear seat in a motor vehicle.

BACKGROUND OF THE INVENTION

1. Field of the Invention

THE PRESENT INVENTION relates to a safety arrangement, and moreparticularly relates to a safety arrangement incorporated in a vehicleseat.

2. Description of Related Art

It is known to use, in a vehicle, a seat which is provided with ahead-rest mounted on the back of the seat, the head-rests being adaptedto move forwardly in the event that a rear impact should occur toprovide protection for the occupant of the seat in order to minimise, orobviate whiplash injuries. Such a head-rest may be termed an “active”head-rest.

It has been proposed previously to provide an active head-rest which isactivated when the occupant of the seat is pressed into the back-rest ofthe seat, as a consequence of a rear impact situation. Such a priorproposed arrangement incorporates a head-rest which is mounted forpivotal movement about a horizontal axis adjacent the top of the seat,the head-rest being connected, by appropriate arms, to a pressure platewhich is mounted within the back-rest of the seat. As the torso of theoccupant of the seat is pressed into the back-rest of the seat during arear impact, the pressure plate is moved in a rearward direction, thuscausing the head-rest itself to move forwardly, so that the head-rest isbrought into a position immediately behind the head of the occupant. Anarrangement of this type is shown in U.S. Pat. No. 5,378,043.

This prior proposed arrangement is intended for use in the front seat ofa motor vehicle. Typically the front seat of a motor vehicle has aback-rest formed from an inverted “U”-shaped frame, with appropriatespringing and padding filling the area between the parallel arms of theframe. Typically both the forward facing side and the rearward facingside of the back-rest are made to be soft and flexible so that the seatis not only comfortable for a person sitting in the seat, but also isnot uncomfortable for the knees of a person sitting in the seat behind.Thus, in the prior art arrangement, the pressure plate can moverearwardly relative to the inverted “U”-shaped frame when a rear impactoccurs.

In many vehicles, the rear part of the back-rest of a rear seat isconstituted by a rigid panel. One reason for this is that typically therear part of the back-rest of the rear seat forms an upright walldefining part of the boot or trunk. This wall must be sufficientlystrong to prevent any luggage present in the boot or trunk from enteringthe passenger compartment in a frontal impact situation. Also, in manycases the back-rest of the rear seat may fold downwardly, and then thepanel at the back of the back-rest forms part of a load-bearingplatform.

If a head-rest of the type described in U.S. Pat. No. 5,378,043 were tobe mounted in the back-rest of a rear seat, having a rigid rear panel,the pressure plate would, in a rear impact situation, almost immediatelyengage the rigid rear panel, and thus the head-rest would not be movedsufficiently forwardly to prevent whiplash injuries.

Whilst it might be possible to make the back-rest “thicker”, thuscreating more space for movement of the pressure plate, carmanufacturers tend to prefer seats that are as thin and as light aspossible. Whilst one might contemplate providing a hatch in the rigidplate, adapted to open in the event of a rear impact, to allow thepressure plate to move rearwardly, it is very difficult to provide ahatch whilst still maintaining a rear panel for the seat, which is flat.A flat surface for the rear panel is important when the back-rest of therear seat is folded forwardly so that the panel forms a load-bearingplatform. Also, of course, if the boot or trunk of the vehicle is fullof luggage, luggage would be adjacent the hatch and would prevent thehatch from opening. It is to be understood that if the pressure plate islocated closer to the front surface of the back-rest of the seat, thepressure plate would prove to be uncomfortable.

SUMMARY OF THE INVENTION

The present invention seeks to provide an improved safety arrangement.

According to this invention there is provided a safety arrangement for amotor vehicle, the safety arrangement comprising a head-rest, means tomount the head-rest for pivotal movement about a predeterminedhorizontal axis adjacent the upper part of the back-rest of the seat,and depending means adapted to extend downwardly within the back-rest ofthe seat beneath the predetermined axis, and which carry a pressureplate to be located within the back-rest at a position behind the torsoof an occupant of the seat, so that pressure applied to the pressureplate will cause the head-rest to move, the pressure plate beingpivotally connected to the depending means.

Preferably the depending means comprise parallel arms.

Conveniently the pressure plate is provided with an integral locatingelement extending upwardly above the axis about which the pressure plateis pivotally connected to the depending means, the locating elementbeing releasably connected to the depending means.

Advantageously the locating element is connected to the depending meansby means of at least one spring clip.

Alternatively the locating element is connected to the depending meansby means of at least one frangible element.

Conveniently a locating element is arranged in association with thepressure plate and the depending means in a position above the axisabout which the pressure plate is pivotally connected to the dependingmeans.

Preferably the locating element is deformable.

Preferably the means to mount the head-rest comprise a substantiallyhorizontal bar adapted to be mounted, by means of bearings, on a framewithin the back-rest of the seat, the axis of the horizontal rod beingthe said predetermined axis, the head-rest being connected to the bar.

Conveniently the depending means are connected to and depend from thebar.

In one embodiment of the invention the rear of the back-rest is providedwith a rigid panel.

BRIEF DESCRIPTION OF THE DRAWINGS

In order that the invention may be more readily understood, and so thatfurther features thereof may be appreciated, the invention will now bedescribed, by way of example, with reference to the accompanyingdrawings in which:

FIG. 1 is a schematic side elevational view of a vehicle seatincorporating a safety arrangement in accordance with one embodiment ofthe invention,

FIG. 2 is a front view of the seat of FIG. 1,

FIG. 3 is a view corresponding to FIG. 1 showing the seat in analternate condition.

FIG. 4 is a schematic side elevational view of a vehicle seatincorporating a safety arrangement in accordance with an alternativeembodiment of the invention.

FIG. 5 and FIG. 6 are views corresponding to FIG. 4 showing the seat inalternate conditions.

DETAILED DESCRIPTION OF THE INVENTION

In the described embodiment of the invention a head-rest is provided ona vehicle seat, and the head-rest is adapted to move forwardly whenthere is a rear impact to reduce or obviate whiplash injuries.

Referring to FIG. 1, a vehicle seat 1, intended for use in a rear seat,comprises a squab 2 and back-rest 3. The rear face of the back-rest 3 isin the form of a rigid panel 4. The back-rest 3 is associated with ahead-rest 5. The head-rest 5 is initially mounted in position above theback-rest of the seat and is supported by a pair of parallel supportarms 6. The parallel support arms 6 are connected to a pivotally mountedhorizontal bar 7. The pivotally mounted bar 7 has opposed ends thereofsupported in bearings 8 which are mounted on a horizontal frame member 9located in the back-rest of the seat, the horizontal frame member 9,together with two vertical parallel arm members 10, 11, forming asubstantially rigid inverted “U”-shaped frame contained within the seat.

Two further parallel arms 12 are also connected to the horizontal bar 7,the arms 12 depending within the back-rest of the seat. The lower endsof the arms 12 carry a pressure plate 13. The pressure plate 13 isprovided with upwardly extending lugs 14, 15, which each receive anoutwardly directed pivot pin 16, 17, carried at the lower ends of thearms 12. The pressure plate can thus pivot about the axis of theco-aligned pins 16, 17. In the described embodiment the pressure platecan only pivot in one pivotal direction from the initial position shownin FIG. 1. Pivotal movement in the opposite direction is prevented, forexample by a stop, a ratchet or equivalent device. The pressure plate 13incorporates an upwardly directed locating arm 18, which extendsupwardly between the parallel arms 12. The upper end of the locating arm18 is releasably connected to the arms 12 by releasable catches 19, 20,which may be spring catches, or which may be catches constituted byfrangible elements adapted to break when subjected to a predeterminedforce. One or more springs, or other resilient means (not shown), may beprovided to bias the head-rest to the “initial” position shown in FIG.1.

It is to be appreciated that when the seat is in ordinary use, thehead-rest will be substantially stationary. However, when a vehicle inwhich the seat is mounted is subjected to a rear impact, the torso of anoccupant of the seat will move so that the torso is effectively forcedinto the back-rest 3 of the seat. The torso of the occupant will thenengage the pressure plate 13, and the combination of the pressure plate13, the parallel arms 12, the horizontal bar 7, the arm 6 and thehead-rest 5, will pivot about the axis of the bar 7, the ends of the rod7 rotating within the bearings 8. The head-rest 5 will thus begin tomove forwardly.

The lower-most edge of the pressure plate 13 will strike the rigid panel4 provided at the rear of the back-rest 3. Continuing pressure appliedto the pressure plate 13 by the torso of the occupant of the seat willcause the clips 19, 20 to be released so that the upper part of thelocating arm 18 is no longer connected to the depending arms 12. Thepressure plate is then free to rotate about the axis of the co-alignedpins 16, 17, in its single direction of pivotal movement. As can be seenfrom FIG. 3, this means that the pressure plate 13 will effectivelypivot about the axis of the pins 16, 17, and also its own lower-mostedge, which is engaging the rigid panel 4, will slide down the panel 4,whilst the upper part of the pressure plate 13 continues to moverearwardly, thus moving the lower-most ends of the depending arms 12 toa rearward position in which they substantially abut the rear panel 4.This enables the head-rest 5 to move forward sufficiently to engage thehead of the occupant of the seat, to minimise or obviate the risk of awhiplash injury occurring.

Referring to FIG. 4 and FIG. 5, a vehicle seat 1 intended for use in arear seat with the safety arrangement in accordance with an alternativeembodiment of the invention have a pressure plate 13′ pivotallyconnected to lower ends of the depending arms 12 and carried at thelower ends of the depending arms 12. The pressure plate 13′ extendsupwardly and downwardly from the pivoting axis. The pressure plate is inordinary use held in a position relative the depending arms 12 bydeformable bands 21. As for the embodiment shown in FIGS. 1, 2 and 3will, when a vehicle in which a seat with a safety arrangement accordingto the embodiment shown in FIG. 4 and FIG. 5 is mounted is subjected toa rear impact, the torso of an occupant be forced into the back-rest ofthe seat. The torso will then engage the pressure plate 13′ and thecombination of the pressure plate 13′, the parallel arms 12, thehorizontal bar 7, the arm 6 and the head rest 5 will pivot about theaxis of the bar 7 such that the head rest 5 will begin to moveforwardly. Also for this embodiment the lower-most end of the pressureplate 13′ will strike the rigid panel 4 at the rear of the back-rest 3.Continuing pressure applied to the pressure plate 13′ by the torso ofthe occupant of the seat will cause the bands 21 to deform so that theupper part of the pressure plate will start to rotate about the pivotingaxis. As can be seen from FIG. 5 and FIG. 6, this means that thepressure plate 13′ will pivot about the pivoting axis. The lower part ofthe pressure plate that is engaging with the rigid panel 4 will slidedown whilst the upper part of the pressure plate 13′ continues to moverearwardly, thus moving the depending arms 12 to rearward position inwhich they substantially abut the rear panel 4. This enables the headrest 5 to move forward sufficiently to engage the head of the occupantof the seat, to minimize or obviate the risk of a whiplash injuryoccurring.

It is to be appreciated that the described movement of the head-restbeing effected against a bias provided by the springs or resilientmeans, if provided.

In a further embodiment of the invention the head-rest and the dependingparallel arms are mounted on a horizontal rotatable bar which extendsbetween the two vertical parallel arm members that form the frame in theback of the seat. The rotatable bar itself forms the transverse part ofthe inverted “U” shaped frame.

In the present Specification “comprise” means “includes or consists of”and “comprising” means “including or consisting of”.

1. A safety arrangement for a motor vehicle seat, the safety arrangementcomprising a head-rest, means to mount the head-rest for pivotalmovement about a first predetermined horizontal axis adjacent thesupport part of a back-rest of the seat, and depending means adapted toextend downwardly within the back-rest of the seat beneath the firstpredetermined axis, and which carry a pressure plate to be locatedwithin the back-rest at a position behind a torso of an occupant of theseat, so that pressure applied to the pressure plate will cause thehead-rest to move, characterized by the rear of the back-rest having arigid panel and the pressure plate being pivotally connected to thedepending means such that continuing pressure applied to the pressureplate after the pressure plate strikes the rigid panel causes thepressure plate to pivot relative to the depending means.
 2. Anarrangement according to claim 1 wherein the depending means compriseparallel arms.
 3. An arrangement according to claim 1 wherein thepressure plate is provided with an integral locating element extendingupwardly above a second axis about which the pressure plate is pivotallyconnected to the depending means, the locating element being releasablyconnected to the depending means.
 4. An arrangement according to claim 3wherein the locating element is connected to the depending means bymeans of at least one spring clip.
 5. An arrangement according to claim3 wherein the locating element is connected to the depending means bymeans of at least one frangible element.
 6. An arrangement according toclaim 1 wherein a locating element is arranged in association with thepressure plate and the depending means in a position above a second axisabout which the pressure plate is pivotally connected to the dependingmeans.
 7. An arrangement according to claim 6 wherein the locatingelement is deformable.
 8. An arrangement according to claim 1 whereinthe means to mount the head-rest comprise a substantially horizontal baradapted to be mounted, by means of bearings, on a frame within theback-rest of the seat, an axis of the horizontal bar being the saidfirst predetermined axis, the head-rest being connected to the bar. 9.An arrangement according to claim 8 wherein the depending means areconnected to and depend from the bar.
 10. A safety arrangement for amotor vehicle, the safety arrangement comprising: a head-rest; asubstantially horizontal bar rotatably mountable in an upper part of aback-rest of a seat, the head-rest mounted to the substantiallyhorizontal bar such that the head-rest can be pivotally moved about thesubstantially horizontal bar; at least one depending arm extendingdownwardly from the substantially horizontal bar, the at least onedepending arm capable of being positioned within the back-rest of theseat; and a pressure plate for placement behind a torso of an occupantof the seat, characterized by the at least one depending arm beingpivotally connected to the pressure plate such that pressure applied tothe pressure plate will cause the head-rest to move, and the rear of theback-rest having a rigid panel such that continuing pressure applied tothe pressure plate after the pressure plate strikes the rigid panelcauses the pressure plate to pivot relative to the at least onedepending arm.
 11. An arrangement according to claim 10, wherein the atleast one depending arm comprises two parallel arms.
 12. An arrangementaccording to claim 10, wherein the pressure plate has an integrallocating element extending upwardly above an axis about which thepressure plate is pivotally connected to the at least one depending arm,the locating element being releasably connected to the at least onedepending arm.
 13. An arrangement according to claim 12, wherein thelocating element is connected to the at least one depending arm by atleast one spring clip.
 14. An arrangement according to claim 12, whereinthe locating element is connected to the at least one depending arm byat least one frangible element.
 15. An arrangement according to claim10, wherein a locating element is arranged in association with thepressure plate and the at least one depending arm in a position above anaxis about which the pressure plate is pivotally connected to the atleast one depending arm.
 16. An arrangement according to claim 15,wherein the locating element is deformable.
 17. An arrangement accordingto claim 10, wherein the substantially horizontal bar is mountable,through the use of bearings, on a frame within the back-rest of theseat.